Theoretical conformational energy calculations are applied to collagen and to peptides which model the behavior of collagen, in a study of the role played by the conformation and in the packing into collagen fibrils. The effect of variation of amino acid sequence upon the intra- and intermolecualr noncovalent interactions and upon the stability of various conformations of the polypeptide chain is analyzed. The goal of this study is the understanding, on the molecular level, of the principles of chemical and mechanical function in normal and aging collagen. A model of hydration, capable of being incorporated into conformational energy calculations, will be applied to energy calculations in collagen. The model is being extended to include interaction between charged groups. The effects of amino acid substitutions on the triple helix-coil conversion will be assessed. Interactions energies will be computed between triple-stranded molecules, to determine how they pack in the collagen microfibril. Results of this study of packing will be applied to other aspects of protein folding.